A neat type , next on my list to purchase. The following notation is from George Eckfeldt's journal. "Struck a few 3 cent pieces of copper & zinc; the size, thickness and diameter about that of the 1857 copper cent. About the middle of 1863." In copper, as illustrated above, there are about 50-60 known.
You have to remember that what we know as the nickel today (the five-cent piece) didn't exist until 1866. Several years earlier, in 1857, copper-nickel small cents replaced the Large Cent (not counting the 1856 pattern cents). These new small cents were much lighter in color than the large cents were and were sometimes called "white cents." Because of their composition, they were also sometimes referred to as "nickels." From 1857 to 1865, they were the only "nickels" around. In 1865, a year before the five-cent nickels came out, the three-cent piece was offered in copper-nickel for the first time since the silver versions were being hoarded. With some folks already used to calling the copper-nickel cents a "nickel" it's not hard to imagine the new three-cent pieces eventually being called three-cent nickels. Of course, today we still call them that to differentiate them from the three cent silvers. Since most of our coinage has been made of copper-nickel since 1965, you could also argue those could be called ten-cent nickels or twenty-five cent nickels and so on, but by the time those came out people were used to the five-cent piece being the only "nickel" they had known for nearly a century.